We propose to identify the genes for autoimmune disease-specific protein antigens by the use of recombinant DNA techniques. The system which we are using lends itself to high level expression of these antigens as hybrid proteins in E. coli. This approach facilitates production of these antigens for the purpose of antigen characterization, generation of antibodies and development of immunodiagnostic tests. A cDNA library will be constructed from human pancreas tissue. Cloning will be into the lambda gt11 system. Clones carrying islet cell antigen sequences will be identified by differential immuno-screening with sera from Type I diabetes patients and sera from normal individuals. With the lambda gt11 system, clones carrying diabetes associated sequences can be induced to express substantial amounts of the pancreas antigen fused to beta-galactosidase (hybrid protein). Because of their large size, these proteins can subsequently be easily purified. The goal of this work is to clone, express and characterize islet cell antigen genes and to develop a simple test for islet cell antibodies using antigens produced by recombinant DNA methods. The use of recombinant DNA techniques gives this methodology the power to identify specific disease associated epitopes. This will facilitate the development of a definitive test for islet cell antibodies.